Papiss Cisse will miss Newcastle's pre-season tour of Portugal amid reports that the striker has refused to back down in an ongoing battle to avoid wearing a shirt sponsored by loan company Wonga.

Manager Alan Pardew had spoken in recent days of his hope that there would be a resolution to the dispute with Cisse, who has expressed a desire not to display the club sponsors name on religious grounds.

While Cisse's fellow Muslim team-mates Cheick Tiote and Moussa Sissoko have told the club they have no issue with wearing the sponsor's logo, the Senegal hit-man who wears the club's fabled No. 9 jersey has taken a different stance.

One proposal has been that Cisse is allowed to wear either an unbranded shirt or a jersey carrying the logo of a charity, yet despite talks with the Professional Footballers' Association and Newcastle officials in a bid to resolve the disagreement, the Daily Mail and Newcastle Chronicle are reporting there has been no breakthrough in the stand-off.

As a result, Cisse will not travel to Portugal with his team-mates, casting a doubt over his future at the club amid suggestions in a BBC report that his relationship with Newcastle officials has become 'strained' over the sponsorship argument.

Cisse is reported to have been training on his own since his return from a summer break last week after refusing to wear the Wonga-branded training kit, yet Pardew confirmed after Tuesday night's friendly at Motherwell that he had included the striker in his squad for the Portugal trip.

However, those plans have now had to be shelved, as Cisse has opted to stand by his beliefs and refuse to wear the club's officially branded kit.